Incompatibility of Mother and Foetus with respect to the Iso-Agglutinogen A and its Antibody

Abstract

Levine''s theory of the pathogenesis of hemolytic disease of the newborn by iso -immunization of the mother to the Rh factor on fetal erythrocytes suggests that there may be comparable intra-uterine incompatibilities of mother and fetus, particularly with regard to the A-B-O groups of Landsteiner. With this end in view, 12 recently published heredity studies have been selected for large size of sample, reliability of technique, and full family data. The mating class A-O (father A, mother O) was chosen for special examination as the largest relevant type of union in most populations. A deficiency both of families with parents A.O and of children in such families as compared with those having parents O.A (father O, mother A) has been shown to be almost entirely attributable to selective loss of children of group A. Examination of the A/O ratio among children of successive birth ranks revealed a steady decline with increasing birth rank in families with parents A.O, suggestive of either (a) an increasing titre of anti-A in the maternal circulation; or (b) increasing placental permeability with increasing maternal age. The data examined and the normal presence of iso-agglutinins in blood of mothers in group O as prescribed by Landsteiner''s reciprocal rule are consistent with the view that A-B-0 iso-immunization acts early in fetal life to produce abortion or miscarriage, giving rise to few cases of erythro-blastosis. Not all families A.O. are equally affected[long dash]i.e. other circumstances, such as differential placental permeability , appear to be involved. A provisional estimate based upon plausible assumptions suggests that A-B-0 iso-immuniza- tion is responsible for the loss of about 25% of the A children expected from marriages A X O, or about 3% of all conceptions.